TWI491651B - Solution casting method - Google Patents

Description

Solution film forming method

The present invention relates to a method of film forming a solution for producing a polymer film.

Various polymer films such as a cellulose oxime film or a cyclic polyolefin film are used for cutting according to the size of the application. The cutting is sometimes performed only with a polymer film before being combined with the member to be combined, but sometimes it is carried out together with the member after being combined with the member to be combined. For example, when a polarizing plate is manufactured, a polarizing film and a polymer film used as a protective film for protecting the polarizing film are attached, and then a dicing process is performed. In addition, the same applies to the case where one of the pair of protective films disposed on both surfaces of the polarizing film is replaced by an optical compensation film (including a retardation film). In this case, the optical compensation film is sometimes used as a protective film.

When the film of the multilayer structure including the polarizing film and the protective film is formed into a polarizing plate and cut into a desired size, the cutting blade is pressed from one of the film faces to cut the multilayer structure film. When the multilayer structure film is cut as described above, cracks may be generated from the cut surface formed by the cut surface toward the inside of the protective film. The protective film which caused such a crack by dicing was evaluated as poor workability, and the commercial value of the obtained polarizing plate was also remarkably low.

Further, when manufacturing a liquid crystal display, a polarizing plate is attached to the glass substrate. When the bonding is performed, when the bonding state is not as expected, the so-called rework is performed after the polarizing plate is peeled off from the glass substrate and then bonded. In the protective film of the polarizing plate, in the rework, especially when peeling off from the glass substrate, a part of the protective film may remain on the glass substrate. Such a protective film which does not peel off the entire portion and remains on the glass substrate is evaluated as poor reworkability, and thus is not preferred.

As a method of producing the polymer film used in the optical application such as the display device as described above, there is a solution film forming method. In the solution film forming method, a dope in which a polymer is dissolved in a solvent is cast on a support to form a cast film, and the cast film is solidified and peeled off, and the peeled cast film, that is, the wet film is dried. A method of producing a polymer film. The solution film formation is known as a dry casting method and a cooling gelation casting method according to a method of solidifying a cast film.

The dry casting method is to dry the cast film to a desired level of drying by which the film is cast by solidification. That is, after the peeling, the cast film is dried until the wet film is in a transportable state.

On the other hand, the cooling gelation casting method is formed into a gel form by cooling the cast film in a state where the solvent residual ratio is extremely high, and is solidified so as to be gelled to the extent that it can be transported even if peeled off.

The above-described dry casting method and the cooling gelation casting method are compared, and since the latter can be peeled off from the support when the solvent residual ratio is high, it is obviously advantageous in terms of production efficiency. However, the polymer film obtained by the cooling gelation casting method is inferior to the polymer film obtained by the dry casting method from the viewpoint of the above-mentioned processing suitability and reworkability.

In order to develop the desired performance, it is effective to manufacture, that is, to increase the amount of film produced per unit time, as in the cooling gelation casting method, and various proposals have been made so far. For example, in the method of Japanese Laid-Open Patent Publication No. 2000-239403, a method of blowing a gas stream at a peeling position where a cast film is peeled off from a support is proposed. According to this method, a film having an intended retardation can be efficiently produced.

Further, in Japanese Laid-Open Patent Publication No. 2001-198933, a film having a blowing speed of 20 m/sec or more is sprayed from the nozzle to the film surface of the wet film immediately after peeling from the support so as to be perpendicular to the film surface. In the case where the solvent residual ratio at the time of peeling from the support is a high value of 100% or more, the cast film can be stably peeled off from the support to produce a flatness. Polymer film.

However, even if the method of the Japanese Patent Laid-Open Publication No. 2000-239403 and the Japanese Patent Laid-Open Publication No. 2001-198933 is applied to a cooling gelation casting method in which the high solvent residual ratio is peeled off and dried, the processing suitability and rework cannot be achieved. Improvement of sex.

Accordingly, it is an object of the present invention to provide a solution film forming method for improving the processability and reworkability of a film produced by a cooling gelation casting method.

The solution film forming method of the present invention includes a cast film forming step, a cast film cooling step, a peeling step, a pressure control step, and a drying step. In the cast film forming step, a cast film is formed by continuously casting a dope in which a polymer is dissolved in a solvent onto a support. In the cast film cooling step, the aforementioned cast film is cooled and solidified. In the peeling step: the cast film is peeled off to obtain a wet film. The cast film was peeled off while the solvent was left. The cast film is peeled off by winding the wet film on the circumferential surface of the roll and conveying the wet film. The roller is disposed such that its longitudinal direction coincides with the width direction of the casting surface of the support. The roller is provided on a side opposite to the support on the conveying path of the wet film. In the pressure control step, the pressure in the second space that is closer to the upstream than the roller is smaller than the pressure in the first space, so that the conveying path of the wet film toward the roller protrudes toward the second space side. The first space is a space on one of the film surfaces of the wet film peeled off from the support. The second space is a space on the other film surface. In the drying step, the wet film is dried to form a film.

In the solution film forming method, it is preferable that the gas in the second space upstream of the roller is sucked by a suction device that sucks the gas, and the peeling position of the casting film is peeled off from the support and the roller The second space between them is decompressed.

Preferably, the suction device includes a chamber that partitions the second space to be decompressed from the external space, and controls a pressure passage in the chamber to control a conveying path of the wet film toward the roller.

Preferably, the angle θ1 formed by the surface of the support and the wet film in the peeling position is set to be in a range of 30° or more and 80° or less by controlling the path.

According to the solution film forming method of the present invention, it is possible to produce a film excellent in workability and reworkability despite the cooling gelation casting method.

The above described features and advantages of the present invention will be more apparent from the following description.

The solution film forming apparatus 10 of Fig. 1 includes a wet film forming apparatus 17, a first tenter 18, a second tenter 19, a roll drying device 22, and a winding device 24. The wet film forming apparatus 17 forms the wet film 16 from the dope 13 in which the polymer 11 is dissolved in the solvent 12. The first tenter 18 is dried while holding the respective side portions of the formed wet film by a holding mechanism (not shown), and is dried until a constant solvent residual ratio is obtained. The second tenter 19 is further dried while holding the side portion of the wet film 16 by a holding mechanism (not shown) and applying an appropriate tension in the width direction. The roller drying device 22 is conveyed by the roller 21 through the wet film 16 of the second tenter 19, and further dried to form the film 23. The winding device 24 winds the dried film 23 into a roll shape. Further, the solution film forming apparatus 10 includes the respective transfer paths between the second tenter 19 and the roll drying device 22 and between the roll drying device 22 and the winding device 24 to cut off the respective end portions of the wet film 16 and the film 23. The slit device (not shown) is omitted.

The wet film forming apparatus 17 is provided with a drum 29 as a support. The drum 29 has a drive mechanism (not shown) that is rotated in the outer circumferential direction by the drive mechanism. By this rotation, the circumferential surface 29a becomes the endless casting surface of the casting dope 13.

Above the drum 29, there is provided a casting die 31 through which the dope 13 flows. The dope 13 is continuously flowed from the casting die 31 to the rotating drum 29, and the dope 13 is cast on the drum 29 to form a casting film 32. Further, regarding the concentrated liquid 13 from the die 31 to the drum 29, a decompression chamber is provided upstream of the rotation direction of the drum 29, but illustration is omitted. The decompression chamber sucks the atmosphere of the upstream side region of the discharged concentrated liquid 13 to decompress the aforementioned region.

The casting film 32 is solidified to the extent that the roller 48 can be conveyed to the first tenter 18, and then peeled off from the drum 29 in a solvent-containing state. The drum 29 has a temperature controller 34 that controls the temperature of the circumferential surface 29a. The temperature of the circumferential surface 29a is controlled by the temperature controller 34, thereby cooling the casting film 32 to a desired temperature and solidifying by the cooling.

At the time of peeling, the wet film 16 is supported by the peeling roller (hereinafter referred to as a peeling roll) 33, and the peeling position PP (refer to FIG. 2) which peels the casting film 32 from the roll 29 is kept constant.

A path control unit 36 that controls the path of the wet film 16 toward the peeling roller 33 is provided upstream of the peeling roller 33.

The method of peeling the casting film 32 from the drum 29 will be described later using other drawings.

A plurality of rolls 48 are provided from the wet film forming apparatus 17 to the transfer portion of the first tenter 18. The wet film 16 formed by peeling is conveyed by these rollers 48 and guided to the first tenter 18.

In the first tenter 18, the end portion of the wet film 16 is held by a holding mechanism (not shown), and the wet film 16 is dried while being conveyed by the holding mechanism. The holding mechanism is a plurality of needles (not shown). The wet film 16 is held by passing the needle through the side ends of the wet film 16. Each of the side end portions is moved in the conveying direction while applying an appropriate tension to the width direction of the wet film 16.

The second tenter 19 downstream of the first tenter 18 also includes a plurality of holding mechanisms for holding the respective end portions of the wet film 16. This holding mechanism is a clip that grips the side end portion of the wet film 16. A plurality of clips impart a predetermined tension to the width direction of the wet film 16 at a predetermined timing.

Each of the first and second tenters 18 and 19 is formed as a chamber that surrounds the transport path. Each of the first and second tenter machines 18 and 19 is provided with a duct (not shown). In these ducts (not shown), a plurality of intake nozzles (not shown) and suction nozzles (not shown) are formed to face the transport path of the wet film 16. The inside of the first and second tenters 18 and 19 is maintained at a constant humidity and a solvent gas concentration by sending the dry gas from the intake nozzle and sucking the gas from the suction nozzle. Drying of the wet film 16 is performed by passing through the insides of the first and second tenters 18 and 19. The wet film 16 is dried in the first tenter 18 until it is held by the clip of the second tenter 19. On the other hand, in the second tenter 19, the timing of the tension in the width direction is taken into consideration, and the degree of drying to be achieved is determined.

The wet film 16 that has passed through the second tenter 19 is removed by a slit device (not shown) by continuously cutting the side end portions of the holding marks by the holding mechanism with a cutting blade. The center portion between the one side end portion and the other side end portion is sent to the roll drying device 22.

When the wet film 16 is sent to the roll drying device 22, it is supported by the circumferential surface of a plurality of rolls 21 arranged in the transport direction. Among these rollers 21, there is a driving roller that rotates in the outer circumferential direction, and is conveyed by the rotation of the driving roller.

The roll drying device 22 is provided with a duct (not shown) through which the dry gas flows out, and is formed as a chamber that separates the space in which the dry gas is supplied from the outside. An exhaust port is formed in the roller drying device 22, and the inside of the roller drying device 22 is maintained at a constant humidity and a solvent gas concentration by discharging the dry gas from the duct and exhausting it from the exhaust port. The wet film 16 is dried to form the film 23 by passing through the inside of the roll drying device 22.

The film 23 dried by the roll drying device 22 is removed by continuously cutting the side end portions with a cutting blade by a slit device (not shown). The center portion between the one side end portion and the other side end portion is sent to the winding device 24 and wound up in a roll shape.

The peeling process will be specifically described with reference to FIGS. 2 and 3 . In Figs. 2 and 3, an arrow Z1 indicates the conveying direction of the wet film 16, and an arrow Z2 indicates the width direction of the wet film 16. Further, the width direction of the circumferential surface 29a coincides with the width direction Z1 of the wet film 16. 2 and 3 are schematic views, and the peeling roller 33 is drawn with respect to the thickness of the wet film 16 to a small extent.

In the following description, the space on the side of the film surface 16a on which one of the wet film 16 is peeled off from the drum 29 is referred to as a first space, and the space on the side of the other film surface 16b is referred to as a second space. The other film surface 16b of the wet film 16 refers to a film surface exposed to the outside when it is the casting film 36. The peeling roller 33 is disposed such that its longitudinal direction coincides with the width direction of the circumferential surface of the drum 29. The peeling roller 33 is provided on the side opposite to the drum 29 on the conveying path of the wet film 16. In other words, since the drum 29 is provided in the first space, the peeling roller 33 is provided in the second space. The peeling roller 33 is provided with a drive mechanism 70 and a controller 71. The controller 71 controls the drive mechanism 70. By the drive mechanism 70, the peeling roller 33 is rotated in the outer circumferential direction at a predetermined rotation speed. When a signal of the speed of rotation of the set peeling roller 33 is input, the controller 71 controls the drive mechanism 70 to rotate the peeling roller 33 at its set speed.

The peeling roller 33 supports the wet film 16 guided by the circumferential surface, and conveys the wet film 16 by rotation. The roller 29 and the peeling roller 33 are disposed so that the wet film 16 is wound around the peeling roller 33, and the transport path downstream of the peeling roller 33 is defined. In this manner, the wetting film 16 is wound around the peeling roller 33, and the wet film 16 is conveyed by the peeling roller 33, whereby the casting film 32 is peeled off from the drum 29.

Further, the peeling roller 33 may not necessarily be a driving roller, and may be a so-called driven roller that is driven by the wet film 16 being conveyed to contact the circumferential surface. In this case, another conveying mechanism is disposed downstream of the peeling roller 33. Further, the wet film 16 is supported by the peeling roller 33, and the wet film 16 is conveyed by the transport mechanism provided, whereby the cast film 32 is peeled off from the drum 29.

The path control unit 36 is provided with a second space between the drum 29 and the peeling roller 33. The path control portion 36 controls the wet film 16 to be transported in an intended path. The path control unit 36 includes a chamber 55, a pump 56, and a controller 57. The chamber 55 separates the space that should be decompressed from the external space. The pump 56 attracts the atmosphere inside the chamber 55. Controller 57 controls the attractive force of pump 56. When the signal of the pressure set in the interior of the chamber 55 is input, the controller 57 adjusts the suction force of the pump 56 to become the set pressure.

The chamber 55 includes a first member 61, a second member 62, a third member 63, a fourth member 64, and a fifth member 65. The first member 61 separates the second space to be decompressed from the outer space on the upstream side in the transport direction Z1 of the wet film 16. The second member 62 separates the second space to be depressurized from the outer space on the downstream side. The third member 63 and the fourth member 64 separate the second space to be decompressed from the outer space on the side of each side in the width direction Z2. The fifth member 65 separates the second space to be decompressed from the lower outer space. Further, the chamber 55 is formed with a first opening 68 that faces the wet film 16 so as to be surrounded by the first member to the fourth member 61 to 64. The outside air of the chamber 55 is sucked from the first opening 68. Among the first to fifth members 61 to 65 of the plate shape, the first to fourth members 61 to 64 are disposed in an upright posture.

The first member 61 is disposed to face the drum 29 and has a curved surface along the circumferential surface 29a of the drum 29. The first member 61 is disposed in such a range that the distance from the drum 29 is in the range of 100 μm or more and 2500 μm or less in consideration of the thickness of the casting film 32. The upstream end 61U of the first member 61 in the conveying direction Z1 is located upstream of the downstream end 29D of the drum 29.

The second member 62 is disposed to face the peeling roller 33 and has a curved surface along the circumferential surface of the peeling roller 33. The second member 62 is disposed in a range of 100 μm or more and 2500 μm or less in consideration of the thickness of the wet film 16 so as to be spaced apart from the peeling roller 33. The downstream end 62D of the second member 62 in the conveying direction Z1 is located closer to the downstream than the upstream end 33U of the peeling roller 33. The second opening 69 is formed in the second member 62. The second opening 69 is connected to the pump 56, and the gas inside the chamber 55 flows out from the second opening 69.

The third member 63 and the fourth member 64 are disposed such that their inner faces are closer to the outer side than the side edges 16e of the wet film 16. Thereby, the wet film 16 during the period in which the path is stabilized does not collide with the third member 63 and the fourth member 64. When viewed from the side, the opposing surface facing the wet film 16 is a curved surface that does not overlap the intended path of the wet film 16 as shown in FIG. 2 in the present embodiment, but may not necessarily be a curved surface.

The inside of the chamber 55 is decompressed by being attracted to the gas. When the inside of the chamber 55 is decompressed, the second space between the drum 29 and the peeling roller 33 is also decompressed, and a lower pressure than the first space can be provided. Thereby, the path is changed from a straight path (symbol A indicated by a broken line in FIG. 2) to a curved path so that the wet film 16 toward the peeling roller 33 approaches the chamber 55 side, as viewed from the side in FIG. 2, The transport path has a convex shape on the second space side. In this way, the path control unit 36 is a gas suction unit that sucks the gas in the second space between the drum 29 and the separation roller 33. The path control unit 36 decompresses the second space between the drum 29 and the separation roller 33 by the suction, and the transmission path of the wet film 16 is convex on the second space side.

By making the transport path of the wet film 16 convex on the second space side, the force applied to the wet film 16 for the peeling and the force applied to the wet film 16 is significantly smaller than in the related art. More force in the applied force is used for peeling. Therefore, the orientation of the polymer of the wet film 16 in the direction along the film surface (hereinafter referred to as the plane orientation) is suppressed, and as a result, both the workability and the reworkability are improved.

In the conventional method, if the force at the time of peeling is too large, the wet film 16 may be cut at the time of peeling. As the manufacturing speed is increased, the solvent residual ratio at the time of peeling is higher, so that the adhesion between the casting film 32 and the drum 29 is greater. Therefore, the more the film forming speed is increased, the greater the force at the time of peeling, and therefore the cutting is easy. On the other hand, according to the above method of the present invention, the force applied for peeling can be further reduced at a constant manufacturing speed, and as a result, the effect of further increasing the manufacturing speed can be obtained. Further, according to the above method, the gas injection of the wet film 16 having a very high solvent residual ratio immediately after the peeling is not performed, so that the smoothness of the film surface of the wet film 16 can be maintained, and contamination by foreign matter can be avoided.

As described above, by controlling the transport path of the wet film 16 toward the peeling roller 33, the angle θ1 formed by the circumferential surface 29a of the drum 29 and the wet film 16 in the peeling position PP can be increased, so that the peeling can be easily controlled at a low level. The power needed.

It is preferable that the angle θ1 formed by the circumferential surface 29a of the drum 29 and the wet film 16 in the peeling position PP is in the range of 30° or more and 80° or less.

When the angle θ1 formed by the circumferential surface 29a of the drum 29 and the wet film 16 in the peeling position PP is increased, the winding center angle θ2 with respect to the peeling roller 33 becomes larger than the winding center angle at the time of the straight path A. If the winding center angle θ2 is easily maintained large, the shape of the conveying path between the drum 29 and the peeling roller 33 is more easily maintained in a convex shape.

Further, the winding center angle θ2 is a central angle of a sector formed by the wet film 16 wound around the winding region 72 of the peeling roller 33 and the center of the cross section of the peeling roller 33.

From the viewpoint of further enlarging the angle θ1 between the circumferential surface 29a of the drum 29 and the wet film 16 and the winding center angle θ2 in the peeling position PP, as in the present embodiment, it is preferable that the peeling roller 33 is not used as the driven roller. It is used as a drive roller. When the shape of the transport path that protrudes on the second space side is held or is largely protruded, the number of revolutions of the drive roller may be lowered. In this manner, in addition to the method of further increasing the transport path toward the wet film 16 of the peeling roller 33 by the suction of the chamber 55, the roller in the peeling position PP can be further enlarged by using the peeling roller 33 as a driving roller. An angle θ1 between the circumferential surface 29a of the 29 and the wet film 16 and a winding center angle θ2.

In the present embodiment, the pressure is reduced so that the second space is lower than the pressure of the first space, but the present invention is not limited thereto. For example, the first space may be pressurized instead of or in addition to the pressure reduction in the second space. Among them, the pressurization is not pressurization under dynamic pressure, but pressurization under static pressure.

The pressurization under static pressure can be performed by repeating the feeding operation and the stopping operation, which are performed by including a part of the downstream side of the drum 29 and a part of the upstream side of the peeling roller 33. A chamber (not shown) surrounds the linear path A of the first space and the wet film 16, and supplies gas to the chamber for a certain period of time; the stop operation stops the feeding operation for a certain period of time. According to this method, it is possible to greatly suppress the occurrence of dynamic pressure such as blowing of gas, and to apply pressure to the wet film 16 from the first space side. Moreover, when the gap between the drum 29 and the peeling roller 33 is set to an extremely small gap of several mm, the pressure difference can be surely applied to the first space and the second space by this method. Further, the gas is sucked from the slit-like opening extending in the width direction Z2, and the smoothness of the film surface can be surely maintained.

There are other methods for providing a pressure difference between the first space and the second space to the drum 29 and the peeling roller 33. For example, there is a method in which the entire chamber surrounding the film forming apparatus 17 (see FIG. 1) is disposed without using the chamber 55 or the chamber (not shown) surrounding the linear path A of the first space and the wet film 16 (not shown) As shown in the figure, a partition member that partitions the internal space is provided to impart the pressure difference. By separately controlling the pressure of each space formed by the partition member, it is possible to impart a pressure difference to the first space closer to the upper side than the transport path of the wet film 16 and the second space closer to the lower side. When the distance between the drum 29 and the peeling roller 33 is 5000 μm or more, it is further preferable to apply the pressure difference by the chamber 55. When the distance between the drum 29 and the peeling roller 33 is less than 5000 μm, the surrounding film may be disposed without using the chamber 55 or the chamber (not shown) surrounding the linear path A of the first space and the wet film 16 A chamber (not shown) that forms the entire device 17 (see Fig. 1) is partitioned by a partition member to impart the pressure difference.

It is preferable that the pressure difference between the first space and the second space is determined by the solvent residual ratio of the wet film 16 from the peeling position PP to the winding region in the peeling roller 33. It is preferable that the larger the solvent residual ratio, the larger the pressure difference, and the larger the propagation path. This is because the greater the solvent residual ratio, the stronger the adhesion of the drum 29 to the casting film 32, and the more easily the wet film 16 is broken.

The peeling position PP is formed toward the center in the width direction Z2 on the downstream side in the rotation direction of the drum 29. Therefore, the force applied to the longitudinal direction of the wet film 16 at the time of peeling becomes larger toward the center in the width direction Z2, and the surface orientation becomes larger. Therefore, it is more preferable that the pressure in the second space is lowered toward the center in the peeling position PP. Thereby, the film 23 whose surface orientation is constant in the width direction Z2 can be manufactured. In order to lower the pressure of the second space toward the center of the peeling position PP, for example, a separate chamber (not shown) is provided inside the chamber 55 to independently control the internal pressures of the chamber and the chamber 55.

The present invention is particularly effective when the polymer 11 (refer to Fig. 1) is a cellulose oxime.

Hereinafter, a comparative example as an embodiment of the present invention and the present invention will be described.

[Example 1]

The film 23 was produced by a cooling gelation casting method. A partition member (not shown) is provided inside the wet film forming apparatus 17 to apply a pressure difference to the first space and the second space. The first space is pressurized so that the pressure is 10 Pa higher than the atmospheric pressure, and the transport path of the wet film 16 is convex in the second space. Further, the pressure in the second space is equal to the atmospheric pressure. Accordingly, the speed ratio of the drum 29 to the peeling roller 33 is changed so that the peeling position PP becomes constant, thereby producing the film 23. In addition, the numerical values of each column of "pressure (Pa) of the first space" and "pressure (Pa) of the second space" in Table 1 are values based on atmospheric pressure. That is, the case where the pressure is equal to the atmospheric pressure is described as 0 (zero), the case where the pressure is higher than the atmospheric pressure is described as a positive value, and the case where the pressure is lower than the atmospheric pressure is described as a negative value.

Regarding the obtained film 23, processing suitability and reworkability were evaluated according to the following methods and standards. The results are shown in Table 1.

(1) Processing suitability

The obtained film 23 was adhered to both sides of the polarizing film by an adhesive to form a polarizing plate. The polarizing plate was punched into a rectangle of 10 cm × 10 cm with a cutter as a sample for evaluation. It was evaluated whether or not cracks occurred from the long side edge of the sample for evaluation, that is, the cut surface to the inside of the film 23, and the degree of the crack to be confirmed was evaluated for the suitability according to the following criteria. The crack may be broken from the cut surface of the film 23 toward the inside, and may be peeled off between the polarizing film and the film 23. According to the following criteria, A to C are the levels of acceptable processing suitability, and D is the level of unsuitable processing suitability.

A: No crack is observed, or although cracking occurs, the crack range that occurs is controlled to be less than 25% of the length of the long side.

B: The range in which the crack occurs is controlled in the range of 25% or more of the length of the long side to less than 50%.

C: The range in which cracks occur is controlled within a range of 50% or more of the length of the long side and less than 75%.

D: The range in which cracks occur is 75% or more of the length of the long side.

(2) Rework

The obtained film 23 was adhered to both sides of the polarizing film by an adhesive to form a polarizing plate. After the polarizing plate is attached to the glass substrate, it is peeled off from the glass substrate. The degree of residual peeling of the film 23 on the glass substrate was visually observed, and the reworkability was evaluated according to the following criteria. According to the following criteria, A to C are the levels of reworkability, and D is the level of rework failure.

A: No residue was observed at all.

B: There is little degree of residual shedding.

C: Although there is little residual shedding, there is no problem in practical use.

D: There is a lot of residue falling off.

[Embodiment 2]

A partition member (not shown) is provided inside the wet film forming apparatus 17 to apply a pressure difference to the first space and the second space. The second space is depressurized so that the pressure is 10 Pa lower than the atmospheric pressure, and the transport path of the wet film 16 is convex on the second space side. In addition, the pressure in the first space is equal to the atmospheric pressure. Others are the same as in the first embodiment.

[Example 3]

In the form of the route film forming apparatus shown in Fig. 1, that is, the path control unit 36 of Fig. 2, the second space is depressurized so that the pressure is 30 Pa lower than the atmospheric pressure. That is, the differential pressure P2-P1 of the pressure P1 of the first space equal to the atmospheric pressure is subtracted from the pressure P2 of the second space to -30 Pa, so that the differential pressure is set to make the transport path of the wet film 16 on the second space side. Become a convex shape. The peeling roller 33 is a driving roller. Accordingly, the speed ratio of the rotation of the drum 29 and the peeling roller 33 is adjusted so that the peeling position PP becomes constant, thereby producing the film 23.

[Example 4]

The path control unit 36 further decompresses the second space from the first space (the differential pressure P2-P1 is -100 Pa), and the transmission path of the wet film 16 is convex on the second space side, so that θ1 is 80°. The pressure in the first space is equal to the atmospheric pressure. Except for this, it was carried out in the same manner as in the third embodiment.

[Example 5]

The path control unit 36 further decompresses the second space from the first space (the differential pressure P2-P1 is -30 Pa), and the transmission path of the wet film 16 is convex on the second space side. The pressure in the first space is equal to the atmospheric pressure. The respective speeds of the drum 29 and the peeling roller 33 were changed to adjust the speed ratio of the both, so that the angle θ1 formed by the circumferential surface 29a of the drum 29 and the wet film 16 in the peeling position PP was 30°. Except for this, it was carried out in the same manner as in the third embodiment.

[Embodiment 6]

The path control unit 36 further decompresses the second space from the first space (the differential pressure P2-P1 is -30 Pa), and the transmission path of the wet film 16 is convex on the second space side. The pressure in the first space is equal to the atmospheric pressure. The respective speeds of the drum 29 and the peeling roller 33 were changed to adjust the speed ratio of the both, so that the angle θ1 formed by the circumferential surface 29a of the drum 29 and the wet film 16 in the peeling position PP was 80°. Except for this, it was carried out in the same manner as in the third embodiment.

[Embodiment 7]

The path control unit 36 further decompresses the second space from the first space (the differential pressure P2-P1 is -30 Pa), and the transmission path of the wet film 16 is convex on the second space side. The pressure in the first space is equal to the atmospheric pressure. The respective speeds of the drum 29 and the peeling roller 33 are changed to adjust the speed ratio of the both, so that the angle θ1 formed by the circumferential surface 29a of the drum 29 and the wet film 16 in the peeling position PP is 90°. Except for this, it was carried out in the same manner as in the third embodiment.

[Comparative example]

The film was produced by a cooling gelation casting method in a state where the path control unit 36 was removed from the solution film forming apparatus 10 of Fig. 1 . The pressure difference between the first space and the second space is 0 (zero), and the transport path from the drum 29 toward the wet film of the peeling roller 33 is a straight path as indicated by the symbol A in Fig. 2 . The respective speeds of the drum 29 and the peeling roller 33 were changed to adjust the speed ratio between the two, so that the circumferential surface 29a of the drum 29 and the wet film formed at the peeling position PP were at an angle θ2 of 30°.

The film 23 obtained in each of Examples 2 to 7 and the film obtained in the comparative example were evaluated for workability and reworkability, respectively, according to the same methods and standards as in Example 1.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

10‧‧‧solution film making equipment

11‧‧‧ polymer

12‧‧‧Solvent

13‧‧‧Liquor

16‧‧‧ Wet film

16a, 16b‧‧‧ film surface

16e‧‧‧lateral edge

17‧‧‧ Wet film shape Device

18‧‧‧1st tenter

19‧‧‧2nd tenter

21‧‧‧ Roll

22‧‧‧Roll drying device

23‧‧‧ film

24‧‧‧Winding device

29‧‧‧Roller

29a‧‧‧Sun

29D, 62D‧‧‧ downstream end

31‧‧

32‧‧‧cast film

33‧‧‧ peeling roller

33U, 61U‧‧‧ upstream end

34‧‧‧ Temperature Controller

36‧‧‧Path Control Department

48‧‧‧ Roll

Room 55‧‧‧

56‧‧‧ pump

57‧‧‧ Controller

61‧‧‧1st component

62‧‧‧2nd component

63‧‧‧3rd component

64‧‧‧4th building block

65‧‧‧5th member

68‧‧‧1st opening

69‧‧‧2nd opening

70‧‧‧ drive mechanism

71‧‧‧ Controller

72‧‧‧Winding area

A‧‧‧ straight path

PP‧‧‧ peeling position

Z1, Z2‧‧‧ direction

Θ1‧‧‧ corner

Θ2‧‧‧ center angle

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view of a solution film forming apparatus in which the present invention has been carried out.

2 is a schematic diagram of a path control unit.

3 is a schematic diagram of a path control unit.

16. . . Wet film

29. . . roller

32. . . Cast film

33. . . Stripping roller

36. . . Path control department

55. . . room

72. . . Winding area

29a. . . Weekly

PP. . . Peeling position

Θ1. . . The angle formed by the circumferential surface 29a of the drum 29 and the wet film 16

61. . . First member

A. . . Straight path

Z1. . . The conveying direction of the wet film 16

64. . . Fourth member

62. . . Second member

69. . . Second opening

56. . . Pump

57. . . Controller

71. . . Controller

70. . . Drive mechanism

Θ2. . . Winding center angle

Claims (3)

A method for forming a solution film, comprising the steps of: forming a cast film by continuously casting a polymer dope dissolved in a solvent on a support; cooling and solidifying the cast film; and stripping the stream A film is obtained by stretching the film, and the cast film is peeled off while leaving the solvent, and the wet film is conveyed by winding the wet film on the circumferential surface of the roll to peel off the cast film, and the roll is disposed. The longitudinal direction thereof is aligned with the width direction of the casting surface of the support body, and the roller is provided on a side opposite to the support body on the conveying path of the wet film; and the pressure of the second space closer to the upstream than the roller a pressure smaller than the pressure in the first space so that the transfer path of the wet film toward the roller protrudes toward the second space side, and the first space is a space on one of the film surfaces of the wet film peeled off from the support body The second space is a space on the other film surface, wherein the gas in the second space that is closer to the upstream than the roller is sucked by the suction device that sucks the gas, thereby The second space between the release position and the roller supporting body stripped of the cast film is reduced; and, the wet film was dried and the film is made. The solution film forming method according to claim 1, wherein the suction device includes a chamber that separates the second space to be decompressed from the external space, and controls the wet film orientation by adjusting a pressure in the chamber. The conveying path of the aforementioned roller. The method for forming a solution according to claim 2, wherein By controlling the above-described path, the angle θ1 between the surface of the support and the wet film in the peeling position is in the range of 30° or more and 80° or less.